Also have access to soft brick also . Not traditional but guts from multi sided kiln.

I want to build kiln with hard brick interior, incase I use the more caustic firing techniques, and I'm cheap. And hard bricks are cheaper.

Original idea was simple small cube ( first thought was 3x3 foot). (Olsen book says simple box design is good) But dependent on furniture size. And burner output. With a blanket top. Blanket second layer for walls and saftey grate or non refractory brick outer Layerr. But since I have access to soft brick ill add that in for more,insulation somewhere.

I have 2 burners, pilots and 2 fans. ( will ask questions about burners on another post already started here)

Idea is primarily a forced air propane burner, I'd also like to be able to experimment , with minor reconfiguration, forced air wood burning, salt, sawdust, Venturi burner. ( yeah I'm askin a lot, a man can dream ....)

But would be happy with simple gas fire.

First I need to calculate size of kiln with given bricks and furniture.

Is there a brick calculator to calculate how many bricks of x size to build a cube or wall?

Part of pkg was some old kiln shelves. Pics to follow. Some warped some cracked some pieces. Hodgepodge of sizes and condition. Is there a problem with using warped shelves? Or cracked shelves if properly supported.? How clean do they need to be before kiln wash?Im planning to by posts and/or bricks. To well support shelves.

See pics

Ps. Touchy feely part to follow so feel free skipThe pottery gods have been very kind to me .I've had the jones (desire) to build a kiln since atmospheric firing is not really avaialble from local,community studio. Had some cheap bricks lined up. But fell through..(awwwww)I,joined a local clay club and last meeting they were thinning the library and picked up kiln book for a donation.Well low and behold by impetus from members here and through a small chain of events. ........well snap to the ending today...I got a bunch ofmhard brick, soft bricks, kiln shelves, most of the parts for forced air burner. And then some ....... For free dollars . Yes you read correctly free. Local potter is down sizing and moving.....he said I was doing him a favor!..........(This guy is smiling) ( prolly be sore tommorow moving 200 ish bricks into to truck and then out of truck)

Also have access to soft brick also . Not traditional but guts from multi sided kiln.

I want to build kiln with hard brick interior, incase I use the more caustic firing techniques, and I'm cheap. And hard bricks are cheaper.

Original idea was simple small cube ( first thought was 3x3 foot). (Olsen book says simple box design is good) But dependent on furniture size. And burner output. With a blanket top. Blanket second layer for walls and saftey grate or non refractory brick outer Layerr. But since I have access to soft brick ill add that in for more,insulation somewhere.

I have 2 burners, pilots and 2 fans. ( will ask questions about burners on another post already started here)

Idea is primarily a forced air propane burner, I'd also like to be able to experimment , with minor reconfiguration, forced air wood burning, salt, sawdust, Venturi burner. ( yeah I'm askin a lot, a man can dream ....)

But would be happy with simple gas fire.

First I need to calculate size of kiln with given bricks and furniture.

Is there a brick calculator to calculate how many bricks of x size to build a cube or wall?

Part of pkg was some old kiln shelves. Pics to follow. Some warped some cracked some pieces. Hodgepodge of sizes and condition. Is there a problem with using warped shelves? Or cracked shelves if properly supported.? How clean do they need to be before kiln wash?Im planning to by posts and/or bricks. To well support shelves.

See pics

Ps. Touchy feely part to follow so feel free skipThe pottery gods have been very kind to me .I've had the jones (desire) to build a kiln since atmospheric firing is not really avaialble from local,community studio. Had some cheap bricks lined up. But fell through..(awwwww)I,joined a local clay club and last meeting they were thinning the library and picked up kiln book for a donation.Well low and behold by impetus from members here and through a small chain of events. ........well snap to the ending today...I got a bunch ofmhard brick, soft bricks, kiln shelves, most of the parts for forced air burner. And then some ....... For free dollars . Yes you read correctly free. Local potter is down sizing and moving.....he said I was doing him a favor!..........(This guy is smiling) ( prolly be sore tommorow moving 200 ish bricks into to truck and then out of truck)

Build the kiln to fit your shelve size. Those silcon shelves look pretty much beat up. Not sure I would build around those but pick a standard size like 12 x24s and build the kiln to fit them-that way when you buy new shelves they will fit.Lay out your bricks on 1st layer then add the amount for the total hieght you want thats how to calculate whats needed. The roof is a different deal.Those hard bick will take a lot of BTUs to warm up. Grind the shelves with a angle grinder to clean them.Mark

Wood firing is a hard brick show-so you have it right-
Soft bricks do reflect and do not hold heat and cool quicker. They do not hold up near as well to wood and abuse.
I was just mentioning that they will take a bunch of gas to heat up .As they absorb more heat as well as keep it.

I built an oil fired kiln with Empire bricks back in 1972. Went to cone 11 easily. Paid five cents per brick...used..I converted to cone 6 in 1980 after the 1970s fuel crisis.
Empire bricks are 8 lbs. tough on the wrists.
marcia

Just a quick comment about the Brick. A number of years ago I had a long discussion with an engineer for A.P. Green company( a company that has since been rolled into a conglomerate) the manufacturer of Empire Brick. Yes the DP brick is excellent for hot face applications. In the course of analyzing my proposed design it turned out that at typical Kiln temperatures hard brick is essentially transparent to heat imput. (Heat leaves as fast as it arrives)

This means your eventual kiln will need insulation to the same extent as an entirely soft brick Kiln. There are a number of coatings for face brick which will slow or reduce the rate of heat transfer. They are made with zirconium compounds if my memory serves.

But I'm going to be using hard brick, inside, ifb ( old electric bricks), Maybe a layer of blanket followed by common brick, So I'm using a combo...... It's going a square like kiln. With fiber or kiln shelf top or soft brick top depending in size.

Which calculation should I use? Soft, hard, or blanket? To calculate btu needs?

Since kiln needs to be built around shelves. How much room, inches should walls be from shelves?
Undecided. But up draft and side draft seem simplest.

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You need to leave space for bag walls and combustion and some extra space around shelves.
Kiln shevles are not the right material for roofs.
Buy a book like Olsens kiln book and or Nils Lous the art of firing.
Mark

You need to leave space for bag walls and combustion and some extra space around shelves.Kiln shevles are not the right material for roofs.Buy a book like Olsens kiln book and or Nils Lous the art of firing.Mark

I think you may need more bricks. Looking at the pics, it doesn't look like a lot. You'll need two courses for the floor minimum. Three is better.
Nils book is more recent than Olsen's. Check out Mel Jacobson's book 21st century Kilns.
As mark says, design the kiln around your shelves and dimensions divisible by 9 and 4.5 standard brick size. I have been getting fiber off of ebay. It is listed all the time from producers. Also, depending what your altitude is, you'll need to adjust the height of the chimney...especially if you are thinking "venturi" for a backup. Forced air burners are less dependent on the pull of the draught of the chimney. Venturis are very dependent of the natural draught.

I think you may need more bricks. Looking at the pics, it doesn't look like a lot. You'll need two courses for the floor minimum. Three is better. Nils book is more recent than Olsen's. Check out Mel Jacobson's book 21st century Kilns.As mark says, design the kiln around your shelves and dimensions divisible by 9 and 4.5 standard brick size. I have been getting fiber off of ebay. It is listed all the time from producers. Also, depending what your altitude is, you'll need to adjust the height of the chimney...especially if you are thinking "venturi" for a backup. Forced air burners are less dependent on the pull of the draught of the chimney. Venturis are very dependent of the natural draught.

I think you may need more bricks. Looking at the pics, it doesn't look like a lot. You'll need two courses for the floor minimum. Three is better. Nils book is more recent than Olsen's. Check out Mel Jacobson's book 21st century Kilns.As mark says, design the kiln around your shelves and dimensions divisible by 9 and 4.5 standard brick size. I have been getting fiber off of ebay. It is listed all the time from producers. Also, depending what your altitude is, you'll need to adjust the height of the chimney...especially if you are thinking "venturi" for a backup. Forced air burners are less dependent on the pull of the draught of the chimney. Venturis are very dependent of the natural draught.

One of the common causes of cold floors on kilns revolves around the mistaken understanding that so many people have that "heat rises". That preception being some sort of a "law" comes from our experiential understanding of our lives....where we experience that HOT GASES rise (like in heated structures). Hot gases rise when suspended in colder gases. Heat energy....... not true.

This mis-understanding is a core concept that I deal with in my Kiln Design and Construction classes.

Heat energy ALWAYS moves from areas of higher concentration to areas of lower concentration. Basic law of thermodynamics. Entropy. Water flows downhill. (Yes... a heat pump can move heat energy seemingly "uphill",...... but that is a separate subject.)

If you want the kiln to fire as evenly as possible using as little fuel to accomplish that feat as possibe........ make sure you don't under-insulate the floor. Otherwise you'll have to adjust the heat DISTRIBUTION pattern in the unit to send more of the overall energy into the floor area than otehrwise necessary.... some of which to also be lost out of the underinsulated floor..... and costing you money in every firing.

So if you decide that the walls and roof structure of a kiln has to have a specific insulation value (heat loss in BTS/ Sq. Ft. / hr.) then the FLOOR should have the same level of insulation. (See * note below also) So if your walls are 9" of brickwork compoised of a 4 1/2" hard brick hot face layer, backed with a 4 1/2" insulating brick layer (of some specific use temp rating) then the floor should also have about this same rating overall.

This can be a little different due to the typical layout of floor bricks being set in the 2 1/2" high layer and the walls being in the 4 1/2" format..... but you CAN lay floors with the brick set in the same (or similar) configuration. The common choices to "match" up to a 9" wall section oftten comes to a decision between a 7 1/2" thick floor and a 10" thick floor. If you understand the insulating values of refractories, you can achieve the SAME insulating value (BTU / Sq. Ft / Hr. conductivity) out of a thinner floor wall section than the side wall structure using DIFFERENT materials........ so the thickness is actuall irrelevant.

The important concept is that the INSULATING value be similar.

The old Rhodes book showing so many 5" thick hardbrick floors in kilns is responsible for SO many kilns with cold bottoms it is amazing. This is something that I commonly end up fixing on a kiln when I am called in to troubleshoot some kiln firing issues.

And if you decide to use fiber in the floor area........ make sure not to compress the fiber too greatly (difficult in a load bearing situation). The more you compress the dead air spaces... the more the loss of insulating value. There is an optimum level of compression for fiber...... used in stuff like Z blocks. Best (easiest) to use "hard versions" of fiber for floors....like board forms.

best,

......................john

(*NOTE: Because there is typically less free air circulation across the cold face of the floor structure, technically the amount of heat energy disappated into the surrounding environment off the cold face is lower than on the vertical wall surfaces and off the roof or arch. So the BTU /Sq,. Ft. / Hr. loss values there is slightly less than the same construction in a wall or roof. But this factor is so small in the overall picture ...as to be inconsequential.)

mark-- stop dissin' (disrespecting) my crappy shelves....... im starting to get the feeling i got hoodwinked into moving them (and they were not light).... there has to be a use some use in this build.....

(sensei john---- you (along with the other ceramic jedi here) are a walking encyclopedia of pottery...... much of the time i read your posts, i get that feeling like im in calculus class... your posts are so information dense..... i read re read.....feel confused ... re read... reread......and pick up so much knowledge (this padwan learner is getting a mad education here)

big thanks to all (but i aint done with the questions, nor the build)

i still have to pick up the soft brick.........i suppose i could fit them in floor without supporting walls if necessary,

how durable are soft bricks (old kiln guts)if i use them as a floor layer???

is hard brick (short side), soft brick, common brick, adequate insulation? can you have too much insulation?how far up chimney do i need refractory material? (how do i calculate)

(also keep in mind im trying to use low cost to free materials here)

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The true sign of intelligence is not knowledge but imagination.
-Albert Einstein

One of the common causes of cold floors on kilns revolves around the mistaken understanding that so many people have that "heat rises". That preception being some sort of a "law" comes from our experiential understanding of our lives....where we experience that HOT GASES rise (like in heated structures). Hot gases rise when suspended in colder gases. Heat energy....... not true.

Very important info there. It's counter-intuitive so lots of potters build kilns with no or less insulation in the floor. Even potters who've build lots of kilns and are considered experts make this mistake.

Ok I'm vaguely familiar with chimney principles....I've seen picture of kilns. Where, afer a certain point switch to stove pipe or red ceramic flue, or common brick. I'm assuming that after a certain point the escaping gasses cool enough to not need refractory material.

Ceramic flue, and stove pipe , and red ceramic flue. are much cheaper than refractory brick. (If I hit the power ball screw the cost)

When building a chimney how far from "exhaust" must refractory brick be used, before transition to lower priced material?

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The true sign of intelligence is not knowledge but imagination.
-Albert Einstein